Piloting system



April i8, 1933. J. A. wlLLouGHB-Y PILQTING SYSTEM Filed Jan. 8; 1929 3 Sheets-Sheet 1 April 18, 19.33.

J. A. WlLLOUGHBY PILOTING SYSTEM 3 Sheets-Sheet 2 IN V EN TOR. Mlloyl Filed Jan. 8, 1929 April 181, 1933.

J. A. WILLOUGHBY PILOTING SYSTEM Filed Jan. 8, '1929 3 Sheets-Slam 3 www - INVENTon atented pr. 18, 1,933l

. JOHN A.. WILOUG-HBY, F CAMBRIDGE, MASSACHUSETTS rrno'rinc SYSTEM Application led January 8, 1,929. Serial No. .331,004.

I My invention relates broadly to an electrical piloting system and more particulari ly to the visual system for indicating the course of mobile bodies with respect to elec- 5 tromagnetically vpropagated waves.

One of the objects of` my invention is to provide a system of electrical piloting in whichthe direction of a'mobile body with respect to an electromagnetic wave may be matic indications given of any deviations of the mobile body from a predetermined course.

Another object of my invention is to pro- 5 vide an automatic switching system for the circuits of a radio receiver for alternatelyrendering eective or ineffective portions of the receiving circuit connected to separate collectors of radio frequency energy located in spaced relation to each other for integrating the effects of the received Venergy upon a local circuit arranged to visually indicate the character of the received energy. v Still another object of my invention is to o provide a circuit arrangement for a radio receiver for use in piloting systems where a visual indicator is utilized to show the normal course and a plurality of indicators employed to show any deviationl from the predetermined course of travel. l Y

A further object of my invention is to provide a receiving circuit fora radio piloting apparatus where accurate indications are rapidly given of deviations from a predetermined course and an independent indicator operated at all times on the mobile body upon which the apparatus is located indicating the course as adhering to or conformingl with a predetermined normal course of travel.

A still further object of my invention is to provide a circuit arrangement for a radio piloting system in which an oscillator alternately supplies energy to independent receiving circuits, rendering the circuits alternately effective to receive hlghfrequency energy by means of collectors disposed in different planes of polarization for actuating by their conjoint effects a' visual indicator system arranged to show any deviaindicated in a continuous manner, and autotion of the mobile body, upon which the system operates, from a predetermined path of electromagnetic wave propagation.' Y.

My invention is particularly applicable for the piloting of aircraft where thecraft flies between two predetermined distant points between which there is propagated electromagnetic energy. The apparatus of m y invention is so designed that-a visual indicator is arranged on board the aircraft and is normally energized to indicate the adherence or conformity -to the course of travelof the aircraft with the line of propagation of the electromagnetic energy.

Deviations from the predetermined course are immediately apparent to the `pilot by a change in condition of the normal path indicated and thev actuation of a selected one of a plurality of deviation indicators for visually indicating the direction of the departure of the craft from the predetermined course; Y My invention will be more fully understood by reference to the following specification and the accompanying drawings in which:

Figure l diagrammatically illustrates one Y form'of my invention showing the independent radio frequency energy collectorswhich are located at spaced points on the mobile ,80

Vbody and showing the circuit connections tothe visualindicating apparatus; Fig. 2 is aA modified form of apparatus in which the deviation from the predetermined course isindicated by the rateof change in condition of a plurality of indicators; and F ig. 3 shows a still further modification of the system f my invention wherein mechanical relays have been eliminated and electrical indicator systems have been employed for indicating the y adherence to or departure from a predetermined course. Referring to the drawings in detail I have shown two separate radio frequency energy collecting systems at X and Y, spaced one from the other and disposed on the mobile body, as for example on the planes of aircraft, in such mannerthat the resiilting fields of the radio frequency energy ccllectors extend in different planes of polarization. The

` ori-ica radio frequency energy collecting system X consists of 'loops 1 and 2 conveniently located on the plane or mobile body at substantially ninety degrees from each other. The terminals of the radio frequency energy collector X may be connected in series or parallel and shunted by tuning condenser 3 and connect to the input terminals of a receiving circuit which may include a radio frequency amplifier system, a detector, and an audio frequency amplifier system but which for the purposes of illustration has been represented in the drawings as a detector tube 4 and gridlczlr and grid condenser 5 in the grid circuit thereof. The output circuit of detector tube 4 connects through audio frequency transformer 6 with the input circuit of a suitable audio frequency amplifier designated for the purposes of my invention by reference character 7. The output circuit of the amplifier system 7 includes the winding 8 of a relay system 9. The output circuit of amplifier tube 7 is completed to source of potential 10. The cathodes for the detector tube 4 and amplifier tube 7 may be heated from the common source of potential indicated at 11.

The radio frequency energy collecting system Y comprises coils 12 and 14 disposed in planes substantially at ninety degrees to each other. rllhe coils are so connected with respect to the connectionof coils 1 and 2 that the resultant fields of the radio frequency energy collector systems X and Y are substantially at right angles. l have indicated this condition by arrows 15 and 16. Coils 12 and 14 may be connected in series or par- Y allel to constitute the radio frequency energy collecting system Y with the circuit terminals thereof connected across tuning condenser 17 to the input circuit of the radio receiving system which for the purpose of illustration has been shown as an electron tube detector V18 with grid leak and grid condenser 19 in the grid circuit, thereof. The out ut of detector 18` is connected through au -o frequency transformer 20 with theinput of a'suitable audio frequency amplifier as represented by electron tube 21 and has relay winding 22 disposed in the output circuit thereof, the output circuit including the source of potential 10 as'shown. The cathod'es of detector tube 18 Aand audio frequency ampliiier tube' 21 are heated from battery system 11. It will be observed that the output circuits of detector tube 4 and detector tube 18 do not contain the usual source of plate potential. I supply a source of plate potential for detector tubes 4 and 18 from an oscillator circuit which includes electron tube 23 having its input and output circuits lelectrostatically coupled by means of condenser system 24. The input and output circuits of the oscillator 23 include inductance systems 25 and 26, the inductance system 25 recante being coupled to an inductance 27 disposed in series in the output circuit of detector tube 4 while inductance 26 is coupled to inductance 28 which is disposed in series in the output circuit of detector tube 18. The oscillator is so timed in its operation that energy will be alternately supplied to the output circuit of detector tube 4 and to the plate circuit of detector tube 18 at predetermined time intervals. This results in the alternate functioning of the detector systems when energy is picked up on collector X or Y.

Reverting to the relay system it will be observed that an armature member 41 is normally positioned between the control magnets 8 and 22 and so long as energy is of the same intensity on'collectors X and Y the relay armature 41 remains in a normal or neutral position. It will be observed that a relay 29 is provided having a winding 29 and an armature 30 with cooperating contact 31 with the normal indicator light S shown at 32 connected across the battery circuit 11 in serieswith the armature 30 and contact 31 normally closed by means of'spring 33. So long as the energy in the collectors Xand Y remains equal there is no tendency for armature 41 to move and indicator light 32 therefore ives a visual indication that the pilot is ying a` straight course in the path of the propagation of electromagnetic waves between two predetermined points.

'The armature 41 may be biased by a spring 42 which tends to maintain the armature in the positionto which it. moves thereby avoiding any rattling orvibration of the armature.

Other means may be provided for controlling the armature 41 such as a dashpot or suitable damper. Shading coils may also be provided so as to prevent chattering of the armature 41. When the plane changes its course one way or the other, thereby departing from the predetermined path of electromagnetic wave propagation, the armature 41 1s moved in the direction of the stronger signal. That is to say, if the signal energy in the collector system X predominates over the signal energy in the collector system Y relay winding 8 attracts armature 41 closing contact 34, energizing indicator light 35 by connecting light 35 across battery system 11,l and simultaneously energizing winding 29 vof relay 29 by connecting winding 29 across battery system 11 through the circuit completed through lead 36 to armature 41 and contact 34. Inasmuch as indicator 35 is energized lthe pilot has the opportunity of swinging the plane back into the course and when this takes place light 35 is extinguished and light 32 is again energized. However, should the pilot bring the plane too far in the Yopposite direction the signal energy in collector system Y predomlnates over the energy in collector X thereby energizing relay winding 22, attracting armature 41 and closarmature system is provided for. the relay ing the circuit through Contact 49, lamp 37 and battery system y11,thereby energizing lamp 37 simultaneously with the opening of the circuit formed by armature 30 and contact 31' by virtue of the energization of relay winding 29.

In the operation of the system illustrated I in Fig. l a predominating signal in collector system X impresses a positive charge on the grid of detector tube 4 through the action of the grid leak and grid condenser 5. When a positive charge is impressed upon the plate of detector tube 4 by the oscillator 23 through, the coupling system and27 there will'be a response in the plate .circuit of tube 4 which through the action of transformer 6-will supply energy to the grid of the amplifier tube -in the solenoid action occurs in the energy collecting system employed for .piloting and substantially circuits. as a mechanical switching system avoiding- 7. Since the plate circuit of tube 7 has a posi-- tive potential vfrom battery l() impressed thereon this will cause the solenoid 8 to move the armature 4l thus bringing about the lfunctions heretofore, explained. When a negative charge is impressedupon theplate circuit of tube 4 from oscillator 23 no eect is produced in the amplification system 7 and even though signaling energy may be coming 8 does not respond. A similar Yl and the associated detector and amplifier The oscillator 23 therefore serves any necessity of manual movement of controls and thus alternately rendering the separate receivers effective and ineffective for integrating the effects of the energy received in the diflerent'planes of polarization upon the automatic -indicating apparatus. In Fig. 2 I have illustrated an arrange-y ment similar to that described in connection with Fig. 1 with the exception that a double windings 8 and 22. The double armatureconsists of movable armature members 38 and 39'each independently movable but elec- -trically'connected together through lead 4Q which extends to one side of battery system 11.' l.

Upon movement of armature 38 to close system 11 andis 'thereby energized when signal-energy predominates in the collector sys- -tem X. Contact 49 connects through lamp 37 with one side of battery system ll so that vwhen the plane: is normally on its course and substantially equal energy is being picked up by collector systems X and Y the lamps 35 and 37 will alternately flicker at a' constant frequency depending upon the period of the oscillator 23. When however, energy predominates in collector system X onlitvhe light connecte-d to the circuit which receives the strongest signal will flicker at the rate determined by` the oscillator and the other light will be extinguished. The object sought inthe circuit of Fig. 2 is to have the pilot iy a .straight 'course which he determinesby-the equal flickering of the lights 35 and 37.

' In. Fig. 3 I have shown a signal system simlar'to the circuits heretofore illustrated except that I- provide neon lamps as means for indicating the amplitude of the energy picked up'by the separate collecting systems. The neon or glow lamp 45 connects through step-up transformer'46 withA the output circuit of amplifier system 2l. When the pilot adheres to -a predetermined normal course the glow lamps A43 and 45 have an equal intensity.. As the pilot deviates from his course the glow lamp. connected to the circuit which picks up the greatest amount of energy glows much brighter or` stronger thanthe other lamp indicating that the pilot is deviating from thev predetermined Course. rIhe oscllator 23 supplies energy alternately to the detect-oi' circuit 4 and detector circuit 18 as described inconnection with Figs. l and 2. In lieuof the neon or glow lamps 43 and 45 I mayA utilize a defiecting meter such eliminates the human equationv from con-` sideration inasmuch asthe circuits may be set and do not requireadjustment from time to time. It is unnecessary that any particular skill be required in the observation of the operation of the system inasmuch as the lighting or glowing of a lamp or deflection of Aa meteris the only factor which mustvbe regarded. The arrangement shown in Fig. 3

lis particularly accurate inasmuch as' by the proper predetermined biasing potential at 48 and 50' in the amplifier system 27 and 2l per- `mits the glow lamps 43 and 45 .to be set .for

operation at predetermined values of ene-roy introduced into the collector systems. The

biasing systems 48 and'50 may be selected of such value as to operate the system at required eiiciency. i

while i have .described my invention in certain ofv its preferred embodiments I desire that it'be understood that modifications may be made and that no limitations upon my inventionare intended other than are imposed by the scope of the append ed claims. What I claim as new and desire to secure by Letters Patent ofthe United .States is as follows: 1

` 1.-In a system for guiding mobile bodies,

Vmeans for receiving electromagnetic energy on either side of a predetermined course, independent receiving circuits connected to each of said means, mechanism for rendering said receiving circuits alternately ,effective and ineective, independent relay ldevices individual to each of said receiving circuits, a third relay device controlled by the operation of the aforesaid relay "devices, a normal course indicator operated under condition of balanced signal in each of said independent y receiving circuits, and separate indicator ap- 5 paratus actuated -by said independent relay devices for indicating the preponderance ofr travel of mobile bodies with respect to a pretiti determined directively propagated electromagnetic Wave channel, a pair o f independent radio frequency energy collecting systems carried by the mobile body, separate radio receiving circuits connected to each of said collectingA systems, relay devices indirvidual to each of said receiving circuits, separate indicators controlled by each of said relay devices, a third relay device controlled by the aforesaid relay devices,an independent indicator apparatus operated by said third relay device, and means for alternately and successively rendering said receiving cir cuits effective and ineffective for operating said indicator apparatus by the conjoint effect Vof the signaling energy pickedup by said collecting systems. U

3. In a system for electrically guiding a mobile body, means disposed in different planes on the mobile body for collecting radio frequency energy in different directions, individual signal receiving means separately connected to said collecting means, frequency generator for rendering said signal receiving means successively effective and ineffective for receiving signal energy'incident upon the collecting means, separate relay means connected to each of said signal receiving means, an independent relay,'means controlled by the aforesaid relay means and means individual to each of said relay means for indicating the preponderance of energyA in either of saidcollecting means.

4. A system for electrically guiding mobile bodies according to an electromagnetically propagated Waye channel, comprising a pair of collectors for receiving radio frequency energy from different directions, in dependent electron tube receiving units connccted with said collectors, an indicator apparatus connected With said receiving units, said apparatus having a pair of branches each controllable by one of said collectors and a third branch controlled by the operation of the aforesaid branches, and means for rendering effective the energy from said collectors each respectively upon its associate ed indicator branch in succession for determining by the conjoint operation 4of said indicator apparatus the course of the electromagnetic propagated wave channel.

5. In a system for electrically guiding mobile bodies with respect to an electromagnetic Wave channel propagated in a predetermined course, a plurality of radio frequency energy ,said relays, rcontrollable by each ofsaid receiving circuits VJfrom an audio,

Leoaeee collecting means, separate electron tube reexciting said receiving units in succession, relays controlled by said receiving circuits,

Ya third relay controlled by the aforesaid relays, indicator mechanism connected with said indicator 'mechanism being for determining said indicator mechanism, saidy mobile body to or departure from said electromagnetic Wave channel.

6. In a system for guiding mobile bodies according to the course of an electromagnetiby the conjoint action of cally propagated wave channel, a plurality of separate receiving means each comprising an electron tube for selectively receiving en ergy from said electromagnetic Wave channel different angular directions with respect to the direction of movement of the mobile body, indicator mechanism including a plurality of branches, V independent receiving circuits disposed between said separate receiving means and at' least two of thel branches of said indicator' mechanism, another of said branches being controlled according to the actuation of the aforesaid branches, :means for alternately and successively exciting the anodes of the electron tubes of said separatereceiving means for rendering eiectivethe received energyiipon the several branches of said indicator mecha nism for visually differentiating the strength of the energy received inthe separate receiving means from said electromagnetically propagated Wave channel.

7. In a system for electrically guiding mobile bodies, coil systems mounted on the mobile body each having a directive characteristic extending at an angle to the line of propagation of an electromagnetic wave defining a predetermined navigable course, separate receiving circuits connected with each of said coi systems, separate indicators connected with said receiving circuits, and a normal course indicator operative upon a balanced condition of said receiving circuits for representing the condition of adherence of the mobile body to the course of the electromagnetic wave propogation,said other indicators being independently operated according to the strength of signal received by said separate receiving circuits for determining the departure of said mobile body from said pre determined course.

S. In a homing system for aircraft navigable according to a predetermined course defined by an eiectromagnetically propagated wave. a pair of directively positioned coil systems each adapted to receive energy from the propagated electromagnetic Wave in a direction disposed at an angle with respect to the sense of direction of the propagated the adherence f4 a pair of directively positioned Y wave system,. yindependent .receiving circuits connected with said coil systems, separate indicatorsconnected to said receiving circuits, and a normal course indicator connected with said aforementioned indicators,`said normal course indicator being operative upon' a condition of balance of energy in said coil systems for representing the adherence of t e aircraft to the predetermined course, 'said normal course indicator being disconnected upon departure of said aircraft from the predetermined course, and said other indicators energized'according to the preponderance of .energy received by` the respective coil systems for determining' the. departure. of the aircraft from the predetermined course.

9. In a system lfor electrically guiding i. ships on a determined navigable course de- -ined by a radio` wave, a pair of ccnl-antenna systems radio 4directively positioned on a ship symmetrically with. referenceto the center line of' the' ship, individual electron tube receiving units connected with` each@ of saidcoil antenna systems, a differential signal responsive device connected to saidA electron tube receiving Yunits, `a normal course visual indicator joperated when the center line of -the-ship coincides with .said

determined navigable coui'se, a right deviation visual'indicator operated when the center line of said ship deviates to the right of said determined navigable course," and a left deviation visual indicator operated when the center line'of said ship 'deviates Y tube receiving u nits connected with each of said coilA antenna systems, a diiferentiall signal responsive device connected to said electron tube receivingl units, a normal course ships on adetermined navigable course devisual 'indicatoroperated when the center line of. the ship 'coincides with saidV determined navigable course, a right deviation.' visual indicatorv operated when Vthe center line of the ship deviates tofthe right of said determined navigable course, anda left deviation visual indicator operated when the center .line-'of the shipdeviates to the left -of said determined navigable course, each of said'yisual indicators consisting pf alight emitting electrically operated device respecv tively 'controlledby said. differential signal .responsive device.

11. In a.- system for electrically guiding 'i lined by -a radio wave, a air of coil-'antenna systems radio directive y positioned .on a.

" ship symmetrically with reference to .thej n vwhen the center line of'the ship deviates to center line of the ship, individual'electron tube receiving units connected with each of said coil-antenna systems, an electron tube oscillator havingfits output connected 'to the anode circuit of each of said electron tube` receivin units, a differential signal responsive device connected to said velectron' tube receiving units,`a normal course visual indicator operated when the center line of the ship coincides with said determined navigable course, a right deviation visual indica'- tor operated when the centerline of the ship deviates to the right of said determined navigable course, and a left deviation-visual indicator voperated when the Acenter line of the shipl deviates tothe leftI of said deter- .controlled by said signal responsive device.v f

12. In a system for electrically guiding` ships on adeterminedv navigable course defined by a radio wave, a pair of coil antenna' systems radio .directively center line Aof the ship, individual electronl tube receiving units connected with each o f said coil antenna systems, an electron tube oscillator having its .output connected to the 'anode circuitv of each of said electron tube receiving units, .individual relays actuated by the output of each of said electron tube receiving units, a third relay controlled b v Vthel aforesaid relays, a right deviation visual indicator operated 'by vone of saidrelays the right ofv said determined navigable course, a left deviation visual indicator o erated by theother of said relays when `e center line of the ship -deviates to the left of said determined navigable'course, a normal course indicatorcontrolled by said third relay each of said visual indicators consisting of a light emitting'electrically operated de- `vice. Y 1 In testimon whereof I atix my si .0HN.A. WILLOUG BY.

--mined navigable course, each,l of said visual indicators being ositioned on a ship'symmetrically with re erence to the ios ature. 11g)l 

